Paperboard cups, cartons and other containers formed from a blank of paperboard are well known in the prior art. Typically, the paperboard blank is precut into desired shape and provided with fold or score lines which facilitate formation of the blank into the desired container shape when it is folded and sealed. The paperboard container must have special structural features to prevent leakage especially at the juncture between its side and bottom walls, when liquid or semi-liquid products are being packaged. One example of a successful carton of this general type is disclosed in the Baker U.S. Pat. No. 3,908,890, issued Sept. 30, 1975, owned by the assignee of the present invention.
To overcome the problem of leakage associated with cup-like paperboard containers, it has been proposed to construct the paperboard carton from a blank including a pair of side wall panels foldably secured to a bottom panel with a pair of foldable gusset sections provided on opposite sides of the bottom wall panel which fold upwardly into engagement with the inner wall of the container. See, for example, U.S. Pat. Nos. 4,020,988 and 4,102,484. Typically, each gusset section comprises a set of three triangular flaps foldably secured together. A first isosceles-shaped flap is foldably attached at its base to one side of the bottom wall panel. A pair of second, identically shaped gusset flaps is connected between the equal sides of the first flap and the respective side wall panels. When the gusset sections are folded to form the container, the free edges of the second gusset flaps tend to align in a vertical, edge-to-edge orientation along the inner side wall of the container. These aligned edges of the gusset flaps are difficult to seal against leakage and often provide pinholes which allow the product to leak from the container.
Other prior art proposals, as exemplified by U.S. Pat. Nos. 2,240,599 and 2,323,287, have required gusset sections with a complicated arrangement of fold lines which necessitate difficult assembly procedures.
Accordingly, it is a primary object of the present invention to provide a cup-like leakproof container formed from a cut and scored blank of paperboard which is uncomplicated in design and convenient to assemble.
Another object of the invention is to provide an improved paperboard container incorporating foldable gusset sections which provide a unique overlapping arrangement of gusset panels when the container is assembled to prevent leakage.
It is also an object of the invention to provide a paperboard blank which is cut and scored in a unique configuration to conveniently form a leakproof container when folded and sealed.
A further object of the invention is to provide a leakproof paperboard container enhanced in strength and rigidity.